Sequence Stratigraphy and Reservoir Characterization of the Upper Campanian-Maastrichtian Succession, Buzurgan Field, Southeastern Iraqi


The Upper Campanian-Maastrichtian succession in Buzurgan oil field of Southeastern Iraq consists of Hartha and Shiranish formations. Three facies associations were distinguished in the studied succession. These include shallow open marine environment within the inner ramp, deep outer ramp and basinal environments. The Hartha Formation in the study area was deposited on a shallow carbonate platform with distally steepened ramp setting. The studied succession represents two 3rd order cycles. These cycles are asymmetrical and start with cycle A which is incomplete where the lower part of the Hartha Formation represents the deep outer ramp facies of the transgressive system tract.and the upper part of the Hartha Formation reflects deposition within the shallow open marine condition of the highstand systems tract. The overlying Shiranish Formation represents the transgressive system tract of cycle B only where it is basinal extent to Aliji Formation. The lower part of the Hartha Formation characterized mainly by microporosity, whereas the middle and upper part of the formation are less porous with interparticle porosity. This high porosity zone includ the lower part of the overlying Shiranish Formation. Where porosity is mainly intraparticle with moldic and fracture porosity being less dominate. The upper part of the Shiranish Formation is less porous.